Field programmable gate arrays (FPGAs), first introduced by XILINX in 1985, are becoming increasingly popular devices for use in electronics systems. For example, communications systems employ FPGAs in large measure because of the re-programmability of FPGAs. In general, the use of FPGAs continues to grow at a rapid rate because they permit relatively short design cycles, reduce costs through logic consolidation, and offer flexibility in their re-programmability.
FPGAs generally have logic blocks in the interior of the chip and input/output blocks (IOBs) around the edges of the chip. The IOBs send and receive signals off and into the chip and also receive power and ground reference voltages from off the chip. One or more clock signals may also be received for synchronizing signals generated on the chip with other signals off the chip.
The semiconductor industry standard operating voltage has in the past been 5 volts, and all devices on a system board have operated at 5 volts. Past IOBs were designed to interface with structures outside the chip using 5 volts as a power supply voltage. However, the industry is presently migrating to lower voltages for faster operation at lower power. Rather than all chips in a system operating at a single voltage, different chips operating at different power supply voltages may be placed into the same system. Therefore, it is desirable that an FPGA placed into that system be able to interface with other chips having a variety of operating voltages, and further that a user's input and output design objects can be mapped to IOBs of the FPGA.
A method and apparatus that addresses the aforementioned problems, as well as other related problems, are therefore desirable.